The development of mass produced fertilizer revolutionized the industrial agriculture industry by maximizing the crop yield that can be grown on a given parcel of land. Fertilizers, along with irrigation systems to relieve dependence on natural precipitation, allow a predictable, optimal yield of agricultural stock from farmland. Fertilizer production employs substantial amounts of ammonia. In solid or liquid states, ammonia salts and solutions are the active components of most synthetic fertilizers used in agriculture, which consume 83% of the world's ammonia and warrant higher demands for ammonia production. The primary industrial method for ammonia synthesis is the Haber-Bosch process, created by Fritz Haber in 1905 and developed for industry by Carl Bosch in 1910. The overall process synthesizes ammonia from molecular nitrogen and hydrogen by feeding the reactants over iron catalysts at a high pressure and temperature, requiring bulky, well-insulated reactors to house the process, and large quantities of natural gas.
The Haber process synthesizes approximately 150 million tons of ammonia each year and has allowed the earth to sustain a greatly increased population. However, the use of natural gas as a source of hydrogen and energy needed to derive nitrogen from atmospheric air have been the subjects of environmental concern. The industrial use and geological extraction of natural gas are known to contribute to carbon dioxide emissions and water pollution, respectively, and today an estimated 59% of natural gas produced in the United States is used in ammonia synthesis to meet the high demand of gaseous hydrogen. Approximately 80% of ammonia synthesized today is eventually converted into urea fertilizer, a dense nitrate that is more stable at room temperature, allowing easier storage and transportation than ammonia.